Comparing the Efficacy of Single and Multiple Visits by Honey and Solitary Bees on Sunflower Seed Production

Sunflower (Helianthus annuus L.) is an important oil seed crop with a considerable acreage of cultivated hybrids in Pakistan. Sunflower crops depend on insect pollination for seed setting, as it attracts diverse pollinator fauna, mainly due to pollen and nectar availability. This study was conducted in the agricultural landscape of Multan, Pakistan, to evaluate the role of native and social bees in sunflower seed production. The abundance and diversity of pollinators were assessed. Effectiveness was tested regarding foraging behavior, including visitation rate, stay time, and seed set efficacy for single and multiple visits (5, 10, 15). Additionally, various reproductive success parameters were recorded: flower head (pseudanthium) diameter, flower head weight, seed weight/flower head, and number of seed/flower head. The results showed that the relative abundance of honey bees was the highest (77%) in both years, followed by solitary bees (17%), while syrphid flies were the least abundant (6%) on sunflower. Among honey bees, Apis mellifera and A. dorsata were the most abundant in both years, followed by the solitary bee Xylocopa sp. Furthermore, in single and multiple seed set efficacy (5 and 10 visits), the solitary bee Xylocopa sp. produced the maximum seeds, followed by A. mellifera. Higher seed production could be achieved with a focused conservation plan of solitary and managed bees on sunflower.